In Iowa, Perry delivered his sharpest criticism yet of Romney. In recent days, Romney has stepped up his criticism of Perry, who leads in national polls in the Republican race for president.

Perry is saying the 2006 Massachusetts health care bill, which required residents to buy insurance, is like the measure signed by President Barack Obama last year. The law is overwhelmingly unpopular with Republicans.

Perry says he thinks important that the GOP nominee "not blur the lines between President Obama and the Republican Party."